Nature of activator radioluminescence in LiF(W) crystal

Abstract

Concentration and azimuthal dependencies of ESR spectrum have been investigated after gamma-irradiation. It has been shown that the activator is metal-oxygen complex of cubic symmetry in which tungsten ion is surrounded by 4 oxygen ions. Charge compensating cation vacancy is in the second coordination sphere of W-ion. The thermoluminescence (TL) curve is characterized by peak at 138K only which is conditioned by thermal delocalization of Vk-centers. The presence of the hole peak only on TL curve allows to suggest the mechanism of activator radioluminescence. Hole recombination on the electron captured by the activator will lead to excitation of the letter owing to hole-electron recombination. The hole recombination on electron colour centers will lead to exciton luminescence excitation and the activator will excite owing to reabsorption. Thus, activator RL, defining spectrum of scintillator luminescence, is conditioned by the process of hole-electron recombination